Simple method of tocopherol determination in plasma lipoprotein fractions using a heparin-Ca precipitation technique

A simple and convenient method using a heparin-Ca precipitation technique, which was devised for determination of serum lipoprotein fractions, was applied to the determination of tocopherol concentrations in individual lipoproteins. Three types of precipitates were prepared from 0.25 ml serum samples plus 0.1 ml of 5% heparin by mixing at 37 degrees C for 30 min with 5 ml of 0.054 M CaCl2 only, 0.054 M CaCl2 in 0.6% NaCl, or 0.054 M CaCl2 in 0.92% NaCl. These three precipitates consisted of chylomicron + VLDL (very low-density lipoprotein) + LDL (low density lipoprotein), chylomicron + VLDL, and chylomicron only, respectively. The tocopherol content of individual lipoproteins was calculated from the concentrations of tocopherol in these three precipitates, and the values obtained by using this technique were very close to those by a standard ultracentrifugation method. Thus, this simple method appears to be suitable for rapid tocopherol assay of a large number of samples.